In this Article, we consider the deployment of public power over the water resource. Federalism, like property, fragments control by dividing and separating power. While fragmentation might work to some extent for relatively discrete aspects of public power, such as those with respect to going to war, entering treaties, issuing money, and raising and maintaining armed forces, when applied to water, questions immediately arise: which unit of government gets to decide about the allocation of private power—property. Which unit of government can deal with those challenges that transcend formal boundaries, such as the environment?